Compiled Laws, Chapter 168. Michigan Election Law § 168.509gg

Sec. 509gg. (1) Subject to subsection (3), the information described in this subsection that is contained in a registration record is exempt from disclosure under the freedom of information act, 1976 PA 442, MCL 15.231 to 15.246. The secretary of state, a designated voter registration agency, or a county, city, township, or village clerk shall not release a copy of that portion of a registration record that contains any of the following:

(2) Except as otherwise provided in this subsection, the last 4 digits of a registered elector's Social Security number contained in a registration record are exempt from disclosure under the freedom of information act, 1976 PA 442, MCL 15.231 to 15.246. The last 4 digits of a registered elector's Social Security number contained in a registration record may only be used by the secretary of state to verify a registered elector's data as provided by the help America vote act of 2002 and to verify a registered elector's status under this act, and must not be used or released for any other purpose.

(3) If an individual preregisters to vote under section 496a,  1 the information contained in the registration record for that individual is confidential and not subject to disclosure under the freedom of information act, 1976 PA 442, MCL 15.231 to 15.246, until that individual is 17- 1/2 years of age. Once that individual is 17- 1/2 years of age, the information contained in the registration record for that individual is subject to the exemptions provided in subsection (1).